Sapphire Radeon RX560 4 GB 'No signal' black screen

I have a brand new RX560 OC card, started doing this from the start. This is the version with one PCI-E power connector on the side.Card causes unrecoverable system crash within 1-2 minutes of starting a game that can only be recovered by power cycling via the button hold or rear PSU switch. Forcing hard reboot does not recover. Occurs on every game in under a minute, screen goes black with 'no signal' displayed, very lagged sound can be heard in background and all fans spool up to maximum.

Is fine on desktop and around windows.

I can replicate the issue almost on command by changing graphics settings in World of Tanks and World of Waships, if I don't do this, they will crash of their own accord but slightly later.

Have reverted back to my original card for the moment, where everything is working fine as watching your PC reboot about 30 times after installing new hardware gets boring real quick.

Games tested:

World of Warships

World of Tanks

Player Unknown's Battlegrounds (happens less than 5 seconds into game world)

The Long Dark

Tried:

All 3 sets of Crimson Relive drivers with clean installs both with and without installing Relive. (From disc (press verion) then 17.7.2 & 17.9.3)

Switched out DP for HDMI

Forcing PCI-E to a fixed speed (100mhz)

Disable anti virus

Disable screen overlays (flux only)

Revert CPU OC to normal

Switching PCIE power connectors

Forcing GPU scaling to Full Panel

Disabled Freesync

Card seating checked

In Wattman:

Underclock (GPU + Mem by 10% and 50Mhz) - results in slightly more stability but by about 30 seconds.

Increase available power both +50% and -50%

Custom temp and fan settings as well as auto.

Established:

Not overheating

Fans are spinning.

Monitor and Card recognised in Device manager.

Possibilites in order of likelyhood imho:

1. Duff card

2. PSU response too slow. (No way to test, no spare PSU)

3. PSU Overcurrent protection

4. Motherboard issue of some kind, perhaps power supply through the slot.